Battery pack and electrical equipment using the same

Abstract

The present invention provides a battery pack that uses an inexpensive general-purpose microcomputer to monitor the voltage of each battery cell. The battery pack (100) includes: a plurality of battery cells (105-107) connected in series; a plurality of voltage detection units (171-173) that detect the voltage of each battery cell; and a microcomputer (150) that measures the voltage of the battery cell based on the output of each voltage detection unit, wherein each voltage detection unit is provided with a switching control circuit (181-183) that turns on or off the output from the voltage detection unit (171-173) to the microcomputer (150). A voltage divider circuit (R3 and R4, R9 and R10, R15 and R16) that divides the detected voltage into a voltage lower than the power supply voltage of the control unit is provided on the output side of the voltage detection unit (171-173), and the microcomputer (150) inputs the voltage divided by the voltage divider circuit to measure the voltage of the battery cells (105-107).

Description

Technical Field

[0001] The present invention relates to a detachable battery pack containing a plurality of battery cells in a casing and an electric device using the battery pack. Background Art

[0002] Battery packs are widely used as power sources in electrical equipment such as power tools that rotate an electric motor by electricity and convert its rotational motion into at least one of the reciprocating motion or rotational motion of an action part, lighting equipment that emits light by electric energy, and audio equipment that emits sound. The battery pack contains a plurality of rechargeable and dischargeable battery cells, which are housed in a synthetic resin housing. The battery pack is provided with a detachable mechanism for the main body of the electrical equipment using a battery side rail portion, and a terminal portion that can be electrically connected during installation. On the other hand, a device side rail portion is provided on the main body of the electrical equipment to guide the battery side rail portion. The electrical equipment for installing or removing the battery pack involves various equipment such as impact screwdrivers, drive drills, grinders, sanders, nail guns, tighteners, positioners, dust collectors, blowers, pumps, high-pressure cleaners, chain saws, lawn mowers, pruning tools, cultivators, flashlights, and radios. The battery pack is required to have a predetermined capacitance, and on the other hand, it is required to be small and light. As an example of an electrical device (power tool) using such a battery pack, patent document 1 is known.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-016114 Summary of the invention

[0006] In the conventional battery pack shown in Patent Document 1, a dedicated battery protection IC is used to protect the lithium-ion battery. In addition, in order to perform various controls on the discharge and charge of the battery pack, it would be very effective if a microcomputer (hereinafter referred to as a "microcomputer" in this specification) is installed in the battery pack. However, if a microcomputer is installed in addition to the battery protection IC, the cost of the battery pack will increase. On the other hand, although battery protection ICs with dedicated microcomputers that specifically protect lithium-ion batteries are sold on the market, they are expensive and a substantial increase in manufacturing costs is inevitable.

[0007] The present invention has been made in view of the above background, and an object of the present invention is to provide a battery pack that monitors the voltage of each battery cell using an inexpensive general-purpose microcomputer, and an electric device using the battery pack.

[0008] Another object of the present invention is to provide a battery pack that suppresses power consumption associated with voltage monitoring of each battery cell, and an electric device using the battery pack.

[0009] Still another object of the present invention is to provide a battery pack and an electric device using the battery pack that can suppress variations in power consumption of each battery cell when monitoring voltage and avoid voltage imbalance of each battery cell.

[0010] Next, representative features of the invention disclosed in this application will be described.

[0011] According to one feature of the present invention, a battery pack includes: a plurality of battery cells connected in series; a plurality of voltage detection units that detect the voltage of each battery cell; and a control unit having a microcomputer that measures the voltage of the battery cell based on the output of each voltage detection unit, wherein a switching control circuit is provided in each of the plurality of voltage detection units, the switching control circuit turning on or off the output from the voltage detection unit to the microcomputer, and a voltage divider circuit that divides the detected voltage into a voltage lower than the power supply voltage of the control unit is provided on the output side of each of the voltage detection units. The microcomputer is configured to measure the voltage of the battery cell based on the voltage divided by the voltage divider circuit. The plurality of battery cells are configured to include at least a first battery cell and a second battery cell from the ground terminal side, and the plurality of voltage detection units are connected to a common ground terminal. The first voltage detection unit detects only the voltage of the first battery cell, and the second voltage detection unit detects the combined voltage of the first battery cell and the second battery cell. In addition, the plurality of battery cells are configured to further include a third battery cell, and the voltage detection unit further includes a third voltage detection unit, and the third voltage detection unit detects the combined voltage of the first battery cell to the third battery cell.

[0012] According to another feature of the present invention, the microcomputer is configured to have output ports corresponding to multiple voltage detection units, and can independently switch multiple switching control circuits. In addition, the microcomputer has multiple input ports corresponding to multiple voltage detection units respectively or an input port commonly connected to multiple voltage detection units, and outputs a charging or discharging stop signal to an external electrical device body or a charger according to a signal input to the input port. The time interval for multiple voltage detection units to detect voltage is changed according to the state of the battery pack and for each voltage detection unit. For example, in the process of charging the battery pack by an external charger, the voltage detection execution time of the voltage detection unit can be controlled to be shorter than the voltage detection stop time.

[0013] According to another feature of the present invention, when the battery pack is installed in an external charger, the voltage detection interval of the voltage detection unit in the process of charging is set to a time interval shorter than the voltage detection interval of the voltage detection unit in the process of waiting for charging. In addition, after the charging is completed in the state where the battery pack is installed in the external charger, the control unit does not perform voltage detection based on the voltage detection unit. And, when the battery pack is installed in the main body of the electrical equipment and is not waiting for discharge, the voltage detection based on the voltage detection unit is performed at a time interval shorter than the voltage detection stop time. And, when the battery pack is installed in the main body of the electrical equipment and is in the process of discharging, the voltage detection based on the voltage detection unit is always performed at a fixed interval. By providing an electrical equipment having a battery pack mounting portion and mounting the above-mentioned battery pack, a battery pack with good performance can be realized at a low price.

[0014] According to another feature of the present invention, a battery pack includes: a plurality of battery cells connected in series; a plurality of voltage detection units that detect the voltage of each battery cell; and a control unit having a microcomputer that measures the voltage of the battery cell based on the output of each voltage detection unit, wherein a switching control circuit is provided in each of the plurality of voltage detection units, the switching control circuit turns on or off the output from the voltage detection unit to the microcomputer, and a voltage dividing circuit that divides the detected voltage into a voltage lower than the power supply voltage of the control unit is provided on the output side of each voltage detection unit. The microcomputer has: the same number of input ports as the number of battery cells and connected to the voltage detection units; and the same number of output ports as the number of battery cells and connected to the switching control circuits. In addition, the plurality of battery cells are configured to include at least the first battery cell, the second battery cell, and the third battery cell from the ground terminal side, and the plurality of voltage detection units are connected to a common ground terminal. The first voltage detection unit detects only the voltage of the first battery cell, the second voltage detection unit detects the combined voltage of the first battery cell and the second battery cell, and the third voltage detection unit detects the combined voltage of the first battery cell to the third battery cell. The microcomputer performs voltage detection by the first to third voltage detection units at non-uniform intervals and in an unequal manner.

[0015] According to the present invention, a voltage monitoring circuit is provided for each battery cell voltage, and the monitoring timing is switched independently for each battery cell under the control of a microcomputer, thereby achieving low circuit consumption and preventing voltage imbalance between battery cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a right side view of the electric device (impact tool 1 ) according to the embodiment of the present invention.

[0017] Figure 2 yes Figure 1 A longitudinal cross-sectional view of an impact tool 1 is shown.

[0018] Figure 3 yes Figure 1 A perspective view of a battery pack 100 is shown in FIG.

[0019] Figure 4 yes Figure 1 Cross-sectional view of section AA.

[0020] Figure 5 1 is a block diagram schematically showing the internal circuit of the battery pack 100 according to the present embodiment.

[0021] Figure 6 is a circuit diagram of the battery pack 100 of this embodiment.

[0022] Figure 7 1 is a flowchart showing a control procedure of the microcomputer 150 in the charging mode of the battery pack 100 .

[0023] Figure 8 1 is a flowchart showing a control procedure of the microcomputer 150 in the non-charging mode of the battery pack 100 .

[0024] Fig. 9 : is a table showing an example of a voltage detection cycle of the microcomputer 150 of the battery pack 100 .

[0025] Fig.10 It is a timing chart of voltage detection by the microcomputer 150 of the battery pack 100 .

[0026] Fig.11 1 is a circuit diagram of a battery pack 100A according to a second embodiment of the present invention.

[0027] Fig.12 This is a timing chart of voltage detection by the microcomputer 150 of the battery pack 100A.

[0028] Description of Reference Numerals

[0029] 1: impact tool; 10: tool body; 11: body shell; 12: main body; 13: handle; 14: hammer case; 14a: protective cover; 15a: air exhaust port; 15b: air intake port; 16: trigger switch; 16a: trigger lever; 17: forward and reverse switching lever; 22: control circuit substrate; 24: motor; 25: rotating shaft; 26: cooling fan; 27: sensor substrate; 28: switch support; 30: speed reduction mechanism; 35: striking mechanism; 36: spindle; 37: striking hammer; 38a: bearing; 38b: bearing; 39: metal part; 40: anvil; 41: blade part; 42: mounting hole; 45: front tool holding part; 46: sleeve; 50: battery pack mounting part; 50a: elastic part Components; 54, 57: rails; 60: terminal; 62: positive input terminal; 63: D terminal; 64: negative input terminal; 65: LD terminal; 100, 100A: battery pack; 101: lower shell; 102a, 102b: latch; 103a, 103b: latch claw; 105: (first) battery cell; 106: (second) battery cell; 107: (third) battery cell; 108a, 108b: screws; 110: upper shell; 111: lower surface; 112: recess; 114: step portion; 115: upper surface; 115a, 115b: notch portion; 120: slot group configuration area; 121-125: slots; 126: raised portion; 126c: stopper; 130: circuit Substrate; 131: battery side terminal; 132: positive terminal; 133: D terminal; 134: negative terminal; 135: LD terminal; 140, 145: guide groove; 144: left and right side; 148: partition; 148a, 148b: joint surface; 150: microcomputer; 151: output port; 152, 152a to 152c: input port; 153a to 153c: output port; 154, 155: input port; 156: output port; 157a, 157b: power supply port; 160: power supply circuit unit; 161: power supply generation unit; 162: power line; 163: ground terminal potential; 164: power switch control circuit; 165: ground line; 166: power supply holding signal; 1 67: signal line; 168: current detection circuit; 169: ground line; 170: voltage detection unit; 171: first voltage detection circuit; 172: second voltage detection circuit; 173: third voltage detection circuit; 176-178: signal lines; 176A, 177A, 178A: signal lines; 181: first circuit control unit; 182: second circuit control unit; 183: third circuit control unit; 186-188: signal lines; 186A-186G: voltage control signal; 187A-187G: voltage control signal; 188A-188G: voltage control signal; 190: communication voltage level shift; 191-193: signal line; 195: battery temperature detection circuit; A1: rotation axis;R1~R18: resistors; TR1~TR6: transistors; VDD: reference voltage. ; DETAILED DESCRIPTION

[0030] [Example 1]

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In this embodiment, an impact tool 1 is used as an example of an electrical device for description. In addition, in this specification, although the up and down directions of the impact tool 1 are set as the directions shown in the drawings for description, the direction of the battery pack single body is based on the installation direction of the battery pack 100, as shown in FIG. Figure 3 and Figure 4 As shown, the front side and the rear side are defined and described.

[0032] Figure 1 1 is a side view of an impact tool 1 according to an embodiment of the present invention. The impact tool 1 is an electrical device consisting of a tool body 10 and a battery pack 100 that can be installed and removed from the tool body 10. The impact tool 1 uses the rechargeable battery pack 100 as a power source and uses the motor as a driving source to drive the rotary striking mechanism. The rotation of the motor is converted into the intermittent striking force of the striking hammer in the rotation direction by the rotary striking mechanism, and the front end tool holding part 45 connected to the striking mechanism part is driven. The main body housing 11 of the impact tool 1 is composed of three parts, namely, a main body 12 formed in a cylindrical shape for accommodating the motor, a handle 13 that is a part held by an operator with one hand, and a battery pack mounting part 50 for mounting a detachable battery pack 100 and arranged at the front end of the handle 13. The main body housing 11 is manufactured in the form of being divided into two parts on the left and right by molding a plastic synthetic resin, and is fixed to each other using a plurality of screws. The handle 13 extends downwardly in a manner substantially perpendicular to the central axis (rotation axis A1) of the main body 12, and a trigger switch for controlling the on / off of the motor is provided at the position where the index finger of the operator is located when the operator holds the handle 13. Figure 2 The operating lever (trigger lever 16a) is provided at the upper rear of the trigger lever 16a, and a forward / reverse switching lever 17 for switching the rotation direction of the motor is provided.

[0033] A battery pack mounting portion 50 is formed at the lower portion of the handle portion 13 to mount the battery pack 100. A detachable battery pack 100 is mounted on the battery pack mounting portion 50. The battery pack 100 accommodates a plurality of secondary batteries such as lithium-ion batteries, and is rated at 10.8V in this embodiment from the viewpoint of the type and number of battery cells accommodated. The battery pack 100 can be used not only for the impact tool 1 but also for various electrical devices that operate at the same rated voltage and have a universal rail mechanism. When the voltage of the battery pack 100 drops, the battery pack 100 is removed from the tool body 10 and charged by an external charger not shown in the figure, so that it can be reused.

[0034] An air intake port 15b formed into a plurality of notches is arranged at the side of the main body 12 and approximately in the center in the front-to-back direction. In addition, an air exhaust port 15a is arranged at a position at a predetermined distance from the rear side of the air intake port 15b. The anvil 40 extends on the front side of the main body 12, and a front end tool holding portion 45 for holding a front end tool is provided at the front end portion of the anvil 40.

[0035] Figure 2 Yes means Figure 1 1 is a longitudinal cross-sectional view of the internal structure of the impact tool 1. The housing of the impact tool 1 is composed of a main body housing 11 (main body 12, handle 13, battery pack mounting portion 50) made of synthetic resin and divided into left and right parts, and a metal integrated hammer case 14 that accommodates the striking mechanism 35. A protective cover 14a made of synthetic resin is installed on the outer peripheral side of the front end of the hammer case 14. Inside the cylindrical main body 12 and the hammer case 14, the motor 24, the speed reduction mechanism 30 using a planetary gear, and the striking mechanism 35 having a striking hammer 37 and an anvil 40 are arranged on the rotation axis A1.

[0036] A trigger switch 16 is disposed on the upper portion of the handle portion 13, and a trigger lever 16a as an operating portion is exposed from the trigger switch 16 to the front side of the main body housing 11. The trigger switch 16 is configured to include a housing having a built-in switch mechanism and an operating portion (trigger lever 16a) provided outside for driving the switch mechanism, and the trigger switch 16 is turned on and off by operating the trigger lever 16a.

[0037] A control circuit substrate 22 equipped with a control circuit is housed inside the handle portion 13, wherein the control circuit has a function of controlling the speed of the motor 24 by the pulling action of the trigger rod 16a. The control circuit substrate 22 is arranged in the vertical direction in a manner parallel to the central axis of the handle portion 13. A microcomputer (not shown) and a semiconductor switching element (not shown) for forming an inverter circuit are mounted on the control circuit substrate 22. A switch support 28 is provided on the outer upper surface of the battery pack mounting portion 50, and the switch support 28 is provided with a switching switch for the action mode, etc. The switch support 28 is provided with various operation buttons such as a setting button for the knocking intensity, a remaining amount check button for the battery pack 100, and lights corresponding to these buttons, etc.

[0038] The motor 24 is a brushless DC motor, and is driven by an excitation current generated by an inverter circuit. A cooling fan 26 for cooling the motor 24 is provided axially rearward of the motor 24 and coaxially with the rotating shaft 25. The rotating shaft 25 is supported by a bearing 38a on the front side and a bearing 38b on the rear side relative to the stator core, and the cooling fan 26 is disposed between the bearing 38b and the stator core. The cooling fan 26 rotates synchronously with the motor 24, and when the cooling fan 26 rotates, air is drawn from the air intake port 15b (see FIG. 15 ) in the center of the main housing 11. Figure 1 ) draws in air to cool the motor 24, and the cooled air is discharged from the air outlet 15a (refer to Figure 1 ) is discharged to the outside.

[0039] A sensor substrate 27 carrying three Hall ICs (not shown) is arranged axially forward of the motor 24 and between the stator core and the bearing 38a. The motor 24 is star-connected, and the ends of the coils (not shown) wound around the stator core are connected to the wiring pattern of the sensor substrate 27 by welding.

[0040] The speed reduction mechanism 30 reduces the output of the motor 24 at a predetermined speed reduction ratio and transmits it to the main shaft 36. Here, a known speed reduction mechanism using planetary gears is used. The main shaft 36 is connected to the output side of the speed reduction mechanism 30, so a main shaft cam groove (not shown) is formed on the outer peripheral surface, and a planetary gear carrier portion of the speed reduction mechanism 30 is formed on the rear side of the shaft portion.

[0041] The hammer 37 is arranged on the outer peripheral side of the shaft of the main shaft 36, and a hammer cam groove is formed on the inner peripheral side. The hammer 37 is held by a cam mechanism using a steel ball (not shown), and the outer peripheral surface of the main shaft 36 contacts a part of the inner peripheral surface of the hammer 37. Figure 2The cam mechanism is omitted in the figure. When the reaction force received from the front end tool is low, the knock hammer 37 rotates in a manner linked to the rotation of the main shaft 36, but when the reaction force received from the front end tool becomes larger, the cam ball of the cam mechanism (not shown) moves, thereby slightly changing the relative position of the knock hammer 37 and the main shaft 36 in the rotation direction, and the knock hammer 37 moves to a large extent to the rear side. The knock hammer 37 is always forced to the front side by the knock hammer spring (not shown), so the movement to the rear side of the knock hammer 37 compresses the knock hammer spring (not shown) while moving.

[0042] At the rear end of the anvil 40, two blade portions 41 serving as struck portions are formed at positions 180 degrees apart in the circumferential direction. The blade portion 41 is in a shape extending radially outward, and is struck by the striking claw of the striking hammer 37. The side surface in the rotation direction of the blade portion 41 is formed with two surfaces: a struck surface that is struck when the striking hammer 37 rotates in the tightening direction, and a struck surface that is formed on the opposite side and struck when it rotates in the loosening direction. The main shaft 36 and the rotating body of the anvil 40 are supported on the hammer case 14 on the front side by a metal part 39. The front end tool holding portion 45 is configured to have a mounting hole 42 with a hexagonal cross-sectional shape extending axially rearward from the front end of the anvil 40, and includes a sleeve 46 that moves forward and backward on the outer peripheral side of the anvil 40.

[0043] The housing of the battery pack 100 is formed by an upper housing 110 and a lower housing 101. Three battery cells 105 to 107 (only 106 is visible in the drawing) are arranged in a horizontal direction with their axes facing the front-to-back direction. A circuit substrate 130 is horizontally arranged above the battery cell 106. A plurality of battery-side terminals (such as the D terminal 123) are arranged upward from the circuit substrate 130 and are engaged with input terminals (such as the D terminal 63) on the power tool body side.

[0044] Figure 3 1 is a perspective view of a battery pack 100 according to an embodiment of the present invention. The battery pack 100 can be mounted on a battery pack mounting portion 50 (see Figure 1) for installation and removal. The lower shell 101 and the upper shell 110 are non-electrical components, such as synthetic resin, and are fixed to each other via four screws 108a, 108b, etc. In order to be installed on the battery pack mounting portion 50, the upper shell 110 is formed with a guide rail mechanism, and the guide rail mechanism is formed with two guide rail grooves 140, 145. The guide rail grooves 140, 145 are grooves whose long sides are parallel to the mounting direction of the battery pack 100 and are recessed inward from the left and right side surfaces 144, 149 of the upper shell 110. The front side end of the groove portion of the guide rail grooves 140, 145 is an open end, and the rear side end is a closed end connected to the front side wall surface of the protrusion 126. The guide rail grooves 140 and 145 are formed in a shape corresponding to the guide rail (not shown) formed on the battery pack mounting portion 50 of the tool body 10. When the guide rail grooves 140 and 145 are engaged with the guide rail of the tool body 10, the latch claws 103a and 103b (in Figure 3 The battery pack 100 is fixed to the tool body 10 by locking the battery pack 100. When the battery pack 100 is removed from the tool body 10, the latches 102a and 102b located on the left and right sides are pushed inward to release the locking state, so that the battery pack 100 is moved to the opposite side of the installation direction in this state.

[0045] A flat lower surface 111 is formed on the front side of the upper shell 110, and an upper surface 115 that is higher than the lower surface 111 is formed near the center. The lower surface 111 and the upper surface 115 are formed in a stepped shape, and their connecting portion forms a step portion 114 that forms a vertical plane. The front side portion from the step portion 114 to the upper surface 115 forms a groove group configuration area 120. In the groove group configuration area 120, a plurality of grooves 121 to 125 are formed in a manner extending from the front step portion 114 to the rear side. The grooves 121 to 125 are portions that are cut away in a manner having a predetermined length in the battery pack installation direction, and a plurality of battery side terminals 131 to 135 (to be described later in detail) that can be mated with the device side terminals of the tool body 10 or an external charging device (not shown) are arranged inside the cut-away portion. Figure 4 The grooves 121 to 125 are formed so that the terminal of the electric tool body can be inserted by sliding from the lower surface 111 side to the rear side.

[0046] As for the slots 121 to 125, the slot 121 on the side close to the guide slot 140 on the right side of the battery pack 100 becomes the insertion port of the positive terminal (C+ terminal) for charging. The slot 122 adjacent to the slot 121 becomes the insertion port of the positive terminal (+ terminal) for discharging. In addition, the slot 124 on the left side of the battery pack 100 becomes the insertion port of the negative terminal (- terminal). In addition to the positive terminal and the negative terminal, two signal terminals for signal transmission used to control the battery pack 100 and the tool body 10 and the external charging device (not shown) are also configured. Here, there are provided: a D terminal slot 123, which receives the start signal of the tool body 10 or the external charger to the microcomputer on the battery pack side, and is used to exchange the transmission and reception signal; and an LD terminal slot 125, which outputs the abnormal stop signal (discharge stop signal or charge stop signal) of the microcomputer in the battery pack 100.

[0047] A protrusion 126 is formed on the rear side of the upper surface 115, and the outer shape of the protrusion 126 is formed to protrude upward from the upper surface 115. A concave stopper 126c is formed near the center of the protrusion 126. The stopper 126c is a surface that contacts the protrusion (not shown) of the battery pack mounting portion 50 when the battery pack 100 is mounted. When the battery pack 100 is mounted on the tool body 10, the multiple terminals (device-side terminals) arranged on the tool body 10 and the multiple connection terminals (not shown) arranged on the battery pack 100 are well contacted to form a conductive state. In addition, the latch claws 103a, 103b (103b is not visible in the figure) work to fix the tool body 10 and the battery pack 100. Notch portions 115a, 115b for facilitating injection molding are formed on the upper side portions of the guide grooves 140, 145 in the upper surface 115.

[0048] A substantially rectangular parallelepiped recess 112 is formed on the front side of the lower surface 111. The recess 112 is a concave-convex portion for identifying whether the battery pack 100 is properly mounted on the tool body 10, and engages with a protrusion (not shown) formed on the tool body 10 side.

[0049] Figure 4 yes Figure 1A cross-sectional view of the AA portion. In the battery pack 100, three lithium-ion batteries rated at 3.6V are housed in a space defined by matching the openings of the upper shell 110 having an opening on the lower side and the lower shell 101 having an opening on the upper side. The battery cells 105 to 107 used are battery cells of the so-called 18650 size, which are 18mm in diameter and 65mm in length. However, battery cells of other sizes and shapes may also be used. The battery cells 105 to 107 are roughly housed in the lower shell 101 in such a manner that the axial direction becomes the front-to-back direction, and a synthetic resin partition 148 is covered on the upper portion thereof, thereby stably fixing the battery cells 105 to 107.

[0050] The partition 148 is manufactured by integrally molding a synthetic resin such as plastic, which is a non-conductive material, and functions as a mounting base for holding the circuit substrate 130 on its upper portion. The partition 148 is shaped to cover the upper half of the outer circumference of the battery cells 105 to 107, and the joint surfaces 148a and 148b that contact the inner wall surface of the lower shell 101 are formed at the left and right ends. The circuit substrate 130 becomes a mounting base for welding a plurality of battery-side terminals 131 to 135, and is equipped with circuit components for battery control such as a microcomputer. Although in Figure 4 Although not visible in the AA cross section, screw holes are formed in the circuit substrate 130, and the circuit substrate 130 is fixed to the spacer 148 by screws (not shown).

[0051] The battery pack mounting portion 50 of the tool body 10 is provided with guide rails 54 and 57, which protrude inward from the inner wall portions on both sides and extend in the longitudinal direction in the front-rear direction. The terminal portion 60 is fixed to the bottom of the battery pack mounting portion 50 and is located at the upper portion of the space sandwiched between the guide rails 54 and 57 when viewed in the left-right direction. An elastic member 50a such as an elastomer is provided on the outer peripheral surface of the battery pack mounting portion 50 in a manner continuous with the outer peripheral surface of the handle portion 13.

[0052] The guide rails 54 and 57 are formed to extend in the front-rear direction and have an upper surface and a lower surface, which are engaged with the inner upper wall and the inner lower wall of the guide rail grooves 140 and 145 of the battery pack 100 in a manner of contacting. The terminal portion 60 is manufactured by integrally forming a non-conductive material such as a synthetic resin, and a plurality of metal terminals such as a positive input terminal 62, a D terminal 63, a negative input terminal 64, and an LD terminal (abnormal stop terminal) 65 are cast therein. The battery side terminals 131 to 135 corresponding to the terminal portion 60 are located in the grooves 121 to 125 (see Figure 3 )'s inner space.

[0053] Figure 51 is a block diagram showing a circuit structure of a battery pack 100 having a microcomputer 150. When the battery pack 100 is mounted on the tool body 10, Figure 4 The positive input terminal 62, negative input terminal 64, and D terminal 63 on the tool body 10 side are connected to the battery side terminals (positive terminal 132, negative terminal 134, and D terminal 133) of the battery pack 100. The secondary batteries contained in the battery pack 100 are three lithium ion battery cells 105 to 107, and the positive side outputs of these connected in series are connected to the positive terminal 132, and the negative side is connected to the negative terminal 134. A current detection circuit 168 is provided in the series connection circuit of the battery cells 105 to 107, and its output is input to the input port 154 of the microcomputer 150 using a signal line 167. The structure of the current detection circuit 168 is various, but in the simplest structure, a shunt resistor (not shown) is interposed in the series connection circuit of the battery cells 105 to 107, and the voltages at both ends of the shunt resistor are input to the input port 154 of the microcomputer 150 via the signal line 167. In this case, two signal lines 167 are required, and two input ports 154 having an A / D conversion function are required. The negative electrode side of the first battery unit 105 is grounded through the ground line 169, and thus has a ground terminal potential.

[0054] The microcomputer 150 performs predetermined calculation processing according to the program, and a general-purpose single-chip microcomputer sold on the market can be used. Although not shown in the figure, the microcomputer 150 is configured to include a central processing unit (CPU), a timer for measuring the time of the calculation processing of the CPU, a ROM (Read only memory) for executing the program executed by the CPU, and a RAM (Random Access Memory) for the work area of ​​the calculation processing of the CPU. The microcomputer 150 is provided with a plurality of input ports (152a to 152c, 154, 155), and the analog signal input to the microcomputer 150 is converted into a digital signal (A / D conversion). The microcomputer 150 is also provided with a plurality of output ports (151, 153a to 153c, 156), and the instruction signal (digital signal) from the CPU is output as an analog signal (predetermined voltage value).

[0055] The voltage detection unit 170, which is composed of the first voltage detection circuit 171, the second voltage detection circuit 172, and the third voltage detection circuit 173, is connected to the positive side terminals of the three battery cells 105 to 107. The voltage detection unit 170 is composed of the first voltage detection circuit 171, the second voltage detection circuit 172, the third voltage detection circuit 173 and the first circuit control unit 181, the second circuit control unit 182, and the third circuit control unit 183. The outputs of the first to third voltage detection circuits 171 to 173 are connected to the input ports 152a to 152c of the microcomputer 150. Although not shown in the figure, the first to third voltage detection circuits 171 to 173 are also connected to the ground terminal potential respectively (hereinafter Figure 6 ), so they output voltage signals proportional to the voltage difference between the ground terminal potentials to the microcomputer 150 through signal lines 176 to 178. The first to third voltage detection circuits 171 to 173 do not always send the detection output to the microcomputer 150, but use the first to third circuit control units 181 to 183 to operate within the time window set as the voltage detection ON, and use the signal lines 176 to 178 to send the voltage signal. In other words, the input signals of the first to third circuit control units 181 to 183 are input from the output ports 153a to 153c of the microcomputer 150 through the signal lines 186 to 188, and the first to third circuit control units 181 to 183 function as switching control circuits.

[0056] The first voltage detection circuit 171 is input with a start signal (gate signal to be described later) via the signal line 186, and the output of the first voltage detection circuit 171 is sent to the microcomputer 150 via the signal line 176 only during the period of inputting the gate signal. Similarly, the second voltage detection circuit 172 and the third voltage detection circuit 173 are also controlled to be turned on or off by the second circuit control unit 182 and the third circuit control unit 183, respectively. The three output ports (D / A ports) 153a to 153c of the microcomputer 150 are allocated to transmit signals to the first to third voltage detection circuits 171 to 173, so the on / off control using the first to third circuit control units 181 to 183 can be performed independently of the microcomputer 150. In addition, in the battery pack 100 of the present embodiment, the number of battery cells (105 to 107) used is three, but when the number of battery cells is set to n (where n is a natural number), n of the plurality of output ports (D / A ports) of the microcomputer 150 are allocated to the control of the circuit control unit. The battery temperature detection circuit 195 includes a thermistor attached to, for example, any one of the battery cells, for example, the outer periphery of the battery cell 106 disposed in the center of three, and its output is output to the microcomputer 150 .

[0057] The power circuit unit 160 generates a power source VDD for the operation of the microcomputer 150, for example, a constant voltage of 3.3V DC, and supplies it to the microcomputer 150 through the power line 162. The power generation unit 161 generates a constant voltage of 3.3V from the positive side of the third battery unit 107 and the ground terminal potential 163, and supplies it to the microcomputer 150. The power switch control circuit 164 is a circuit for starting (turning on) the power generation unit 161. When a high-level signal is sent from the power switch control circuit 164, the power generation unit 161 is turned on, and when a high-level signal is extracted, the power generation unit 161 is turned off. That is, the power switch control circuit 164 has a switch function to start or stop the power generation unit 161, so when the start signal is input from the D terminal 133 via the signal line 193, the power switch control circuit 164 starts the power generation unit 161.

[0058] Immediately after the battery pack 100 is attached to an external device (not shown) or after the microcomputer of the external device is activated from a sleep state, the signal input to the D terminal 133 of the battery pack 100 is the operating voltage of the microcomputer (e.g., 3.3V or 5V) when the external device is a device with a microcomputer, and is, for example, the voltage of the battery pack connected to the external device (10.8V in this embodiment) when the external device is a device with a microcomputer. Therefore, a voltage greater than a predetermined voltage is applied to the D terminal 133 of the microcomputer 150, thereby recognizing that the external device is activated, and the power switch control circuit 164 to which the activation signal is input activates the power generation unit 161, thereby supplying power to the microcomputer 150 and activating the microcomputer 150. The microcomputer 150 is provided with two power supply ports 157a and 157b, one of which is connected to a +3.3V power line 162, and the other is connected to the ground via a ground line 165.

[0059] The communication voltage level shifter 190 is used to generate a communication voltage change to Figure 1 The circuit for communicating with the tool body 10 shown or an externally connected device such as an external charger (not shown). The output of the communication voltage level shifter 190 is connected to the input port (A / D port) 155 of the microcomputer via a signal line 191 (for reception by the microcomputer 150), and the input of the communication voltage level shifter 190 is connected to the output port (D / A port) 156 of the microcomputer via a signal line 192 (for transmission by the microcomputer 150).

[0060] Here, the microcomputer 150 is started when the reference voltage VDD is supplied from the power circuit unit 160, and the power supply holding signal 166 is continuously output from the output port 151, thereby maintaining the power circuit unit 160 in an on state even when the signal line 193 from the external connection device becomes a low level. On the other hand, when the microcomputer 150 is started and removed from the external connection device and the signal of the signal line 193 disappears or drops to a low level, the power circuit unit 160 can continue to operate. In addition, the microcomputer 150 cuts off the output of the power supply holding signal 166 by its own judgment, thereby stopping the operation of the power circuit unit 160 and shutting down itself.

[0061] The microcomputer 150 uses the outputs of the first to third voltage detection circuits 171 to 173 to detect and monitor the voltages at both ends of each battery cell and manage discharge and charge. This also includes functions such as obtaining cell balance and detecting disconnection. However, the specific control method for charge and discharge management of the battery cells 105 to 107 can be controlled by using a known battery management method, so detailed description is omitted here. In addition, the microcomputer 150 has a function of detecting an abnormal state such as overcurrent or abnormal overheating via the LD terminal 135 (see Figure 4 ) stops the tool body 10 from operating or stops the external charger from charging, but Figure 5 The circuit diagram of LD terminal 135 and the output port of microcomputer 150 corresponding to LD terminal 135 are omitted. As described above, microcomputer 150 functions as a so-called battery protection IC, thereby measuring the voltage of first to third battery cells 105 to 107, measuring the magnitude of the current flowing through the battery cells based on the output of current detection circuit 168, and controlling both charging and discharging so as to maintain the state of first to third battery cells 105 to 107 normally.

[0062] Next, use Figure 6The circuit diagram of illustrates the detailed circuit structure of the first to third voltage detection circuits 171 to 173 and the first to third circuit control units 181 to 183. The first voltage detection circuit 171 mainly comprises a transistor TR1 that performs a switching action, the emitter of the transistor TR1 is connected to the positive side of the first battery unit 105, and the collector is connected to the ground via the voltage-dividing resistors R3 and R4. The middle point of the voltage-dividing resistors R3 and R4 is input to the input port 152a of the microcomputer 150 as a voltage detection signal of the first unit 105 and as a signal line 176. The base of the transistor TR1 is connected to the ground via the resistor R2 and the transistor TR2. The emitter of the transistor TR2 is connected to the base of the transistor TR1 via the resistor R2, and the emitter is connected to the ground. The base of the transistor TR2 is connected to the signal line 186 via the resistor R5, and is connected to the output port 153a of the microcomputer 150. When the transistor TR2 is in the on state, the divided voltage of the resistors R1 and R2 is applied to the base, thereby setting the emitter-collector to the on state, thereby setting the resistor R6. In addition, when the base signal of the transistor TR1 is open, the emitter and the base are set to 0V, and the off state of TR1 between the emitter and the collector is stably maintained, thereby setting the resistor R1.

[0063] When a high-level signal is input from the microcomputer 150 to the first circuit control unit 181 via the signal line 186, the emitter-collector of the transistor TR2 is turned on, thereby forming a closed circuit of the first battery cell 105-resistor R1-resistor R2-transistor TR2. In addition, the divided voltage of the resistors R1 and R2 is applied to the base of the transistor TR1, thereby turning on the transistor TR1. Thus, a closed circuit of the first battery cell 105-transistor TR1-resistor R3-resistor R4 is formed, and the divided voltage of the resistors R3 and R4 is input to the input port 152a of the microcomputer 150 as the first cell voltage via the signal line 176.

[0064] If the signal line 186 changes from a high state to a low state or is open, the voltage between the base and the collector of the transistor TR2 becomes approximately 0V, so the collector and the emitter of TR2 are cut off. As a result, there is no potential difference between the base voltage of the transistor TR1 and the emitter, so the transistor TR1 is cut off, and the current from the battery cell 105 does not flow through the voltage-dividing resistors R3 and R4. As a result, the signal line 176 becomes equal to the ground state, and no voltage is applied to the input port 152a. As described above, only when a high-level signal is output via the signal line 186, the microcomputer 150 can input the output of the first voltage detection circuit 171 to the input port 152a via the signal line 176.

[0065] The second voltage detection circuit 172 and the second circuit control unit 182 have the same structure as the first voltage detection circuit 171 and the first circuit control unit 181. However, the divided voltage applied to the voltage-dividing resistors R9 and R10 is not the voltage of the second cell 106, but becomes a divided voltage for the combined voltage of the first battery cell 105 and the second cell 106. Similarly, the third voltage detection circuit 173 and the third circuit control unit 183 have the same structure as the first voltage detection circuit 171 and the first circuit control unit 181. Moreover, the divided voltage applied to the voltage-dividing resistors R15 and R16 becomes a divided voltage for the combined voltage of the three battery cells from the first battery cell 105 to the third battery cell 107.

[0066] By setting the circuit configuration as described above, a voltage detection circuit of a battery pack can be realized using a general-purpose microcomputer 150 having multiple input ports and multiple output ports. In addition, the microcomputer 150 can calculate the individual voltages of the battery cells 105 to 107 using the measured values ​​of the three voltage detection circuits 171 to 173 .

[0067] Next, use Figure 7 The flowchart of the embodiment of the present invention illustrates the process of the voltage detection operation of the microcomputer 150 during charging using an external charger. First, when a predetermined DC voltage is input to the power supply circuit unit 160 via the signal line 193, the power switch control circuit 164 causes the power supply generation unit 161 to operate, whereby the reference voltage VDD is supplied to the microcomputer 150, thereby starting the microcomputer 150 (step 201). After starting the microcomputer 150, the steps after step 202 are executed, but these series of processes can be executed in software using a program pre-stored in the microcomputer 150. Immediately after the startup, the microcomputer 150 sets the cycle for voltage detection to "mode 4" (steps 202, 203) as a "non-charging mode" in which no charging operation is performed. The content of "mode 4" will be described later.

[0068] Next, the microcomputer 150 checks the input voltage of the D terminal 133 to determine whether data communication with an external device (power tool body, external charger) is possible (step 204). If data communication is possible, that is, if the external device is connected, it is determined whether the external device is an external charger (step 205). If data communication is not possible in step 204 or if the external device is not a charger in step 205, the microcomputer 150 maintains the "non-charging mode" state unchanged as a voltage detection action (step 251). Figure 8The control process of the microcomputer 150 in the "non-charging mode" is described. When the object with which data communication can be performed is an external charger in step 205, the microcomputer 150 changes to the "charging mode" (step 206) as a voltage detection operation. Next, the microcomputer 150 determines whether to start charging the battery cells 105 to 107 by external charging based on the output from the current detection circuit 168 (step 207).

[0069] In the case where charging is started in step 207, as a voltage detection cycle, the microcomputer 150 sets "mode 1", that is, sets the detection cycle to 5 seconds, and turns on the first to third voltage detection circuits 171 to 173 for 1 second to perform voltage detection, and does not perform voltage detection in the remaining 4 seconds (step 208). In this way, when observing the ratio of the detection time window, the voltage detection execution: voltage detection stop is set to 4:1, so as to control the voltage execution time of the voltage detection unit to be sufficiently shorter than the voltage detection stop time. In the case where charging is not started in step 207, as a voltage detection cycle, the microcomputer 150 sets "mode 2", that is, sets the detection cycle to 30 seconds, and turns on the first to third voltage detection circuits 171 to 173 for 1 second to perform voltage detection, and does not perform voltage detection in the remaining 29 seconds, and shortens the voltage detection execution time (step 211).

[0070] Next, the microcomputer 150 determines whether the battery pack 100 is in a fully charged state based on the voltages detected by the first to third voltage detection circuits 171 to 173 (step 209). Whether the battery pack 100 is in a fully charged state is determined based on whether the voltage of any of the battery cells 105 to 107 reaches the overcharge threshold, and the microcomputer 150 can use the outputs of the first to third voltage detection circuits 171 to 173 to make the determination.

[0071] If the battery is not fully charged in step 209, the process returns to step 207. If the battery is fully charged, the microcomputer 150 sets the cycle for voltage detection to "mode 3" (step 210). "Mode 3" for voltage detection is a control in which the first to third voltage detection circuits 171 to 173 do not perform voltage detection. In addition, the microcomputer 150 uses the LD terminal 135 to send a charging stop signal to the charger side. The charging mode of the battery pack 100 is terminated by the above control.

[0072] Next, use Figure 8The process of the voltage detection operation of the microcomputer 150 when the battery pack is discharged (not charged) is described. The non-charging state mainly refers to the state in which the battery pack 100 is installed and not installed in an external charger (not shown) (step 201). In addition, when the battery pack 100 is removed and stored as a single unit, the microcomputer 150 is shut down. Therefore, unless a startup circuit of the microcomputer 150 is separately provided, the microcomputer 150 cannot detect the voltage of the battery cells 105 to 107.

[0073] In the non-charging mode, the microcomputer 150 first sets the cycle for voltage detection to "mode 4" (step 252). "Mode 4" for voltage detection sets the detection cycle to 5 seconds, of which the first to third voltage detection circuits 171 to 173 are turned on for 1 second to perform voltage detection, and the remaining 4 seconds do not perform voltage detection. Next, if the microcomputer 150 continues to be in an unused state without discharging from the battery pack 100 for a predetermined set time (for example, a threshold value in the range of several seconds to several tens of minutes), the microcomputer 150 sends a self-stop signal from the output port 151, thereby stopping the operation of the power circuit unit 160 and shutting down the microcomputer 150 (step 256). The situation in which step 256 is executed is, for example, a situation in which the trigger lever 16a is not operated for a period of time after the battery pack 100 is installed in the power tool 1 and the microcomputer 150 of the battery pack 100 is temporarily started.

[0074] If the predetermined time has not passed in step 253, the microcomputer 150 determines whether the battery pack 100 is discharged. If the battery pack 100 is not discharged, that is, the trigger lever 6a of the impact tool 1 is not pulled, the process returns to step 252. If the battery pack 100 is discharged in step 254, that is, the trigger lever 6a is pulled, the microcomputer 150 sets the voltage detection cycle to "mode 5" (step 255). "Mode 5" for voltage detection is a control that always performs voltage detection in the first to third voltage detection circuits 171 to 173.

[0075] Fig. 9 is a table showing an example of a voltage detection cycle of the microcomputer 150 of the battery pack 100, and exemplifies Figure 7 and Figure 8The mode is shown in the flowchart. Here, as the detection mode of the battery pack 100, it is divided into two modes, "charging" and "non-charging". The "charging mode" is the mode when it is installed in the external charger, and the other modes are "non-charging mode". There are three control modes of modes 1 to 3 in the "charging mode". Mode 1 is used when detecting the voltage during the charging process. The detection cycle is set to 5 seconds, and the voltage detection is performed only for 1 second in the time window divided by 1 second. No voltage detection is performed in the remaining 4-second time window. Mode 2 is used for voltage detection in a high temperature atmosphere before starting charging. The detection cycle is set to 30 seconds, and the voltage detection is performed only for 1 second in the time window divided by 1 second. Mode 3 is a voltage detection mode before the battery pack 100 is removed from the external charger after charging is completed and fully charged. Mode 3 is a fully charged state, so no voltage detection is performed.

[0076] The "non-charging mode" is a mode when the battery pack 100 is not installed in an external charger. The battery pack 100 is installed in the main body of the electrical device and the microcomputer 150 of the battery pack 100 is activated. It is the state immediately after the battery pack 100 is removed from the main body of the electrical device and before the microcomputer 150 is shut down. After the microcomputer 150 is temporarily shut down when the battery pack 100 is removed, the microcomputer 150 will not be restarted unless it is installed in an external device, so the "non-charging mode" is not executed.

[0077] Mode 4 in the "non-charging mode" is used for voltage detection when the battery pack 100 is installed in the main body of the electrical device. The detection cycle is set to 5 seconds, and the voltage detection is performed only in one time window among the five time windows divided by 1 second. The voltage detection is not performed in the remaining four time windows of 4 seconds. Mode 5 is set to be used for voltage detection when the trigger lever 6a of the main body of the electrical device is pulled (when discharging), and is a constant detection mode in which voltage detection is performed in all time windows among the time windows divided by 1 second.

[0078] Next, use Fig.10 The voltage detection timings in the first to third voltage detection circuits 171 to 173 are described. Fig.10 In (A) to (C), voltage control signals 186A, 187A, and 188A represent outputs from Figure 6The signal levels of the signal lines 186, 187, and 188 of the output ports 153a to 153c of the microcomputer 150 are shown in FIG. The horizontal axis is the time axis, indicating the time T (unit: second), and the vertical axis is the signal level (unit: V), indicating whether it is a high level (high voltage) or a low level (low voltage or 0V). When the voltage control signal (186A, 187A, 188A) is at a high level, the corresponding circuit control unit (181 to 183) operates the voltage detection circuit (171 to 173), and the output of the voltage dividing resistors (R3 and R4, R9 and R10, R15 and R16) is input to the input ports 152a to 152c of the microcomputer 150 via the signal lines 176 to 178.

[0079] Fig.10 (A) is the voltage detection control in "Mode 4" of "Non-charging Mode". Here, in the time window of 1 second, the voltage is detected in the first half and the voltage detection is stopped in the second half. In the voltage control signals 186A and 187A, the voltage is detected in the time window of 0 to 1 second and the time window of 5 to 6 seconds. In this time window, the voltage control signals 186A and 187A are set to a high level only in the first half of 0.5 seconds and are disconnected in the second half of 0.5 seconds. During the period when it is connected, the voltage detection is performed in coordination with the reading cycle of the voltage detection of the microcomputer. For example, when the timing (cycle) of voltage detection is every 1 millisecond, it is sufficient to read the voltage in sequence every 1 millisecond and use the average value of 256ms. On the other hand, the voltage control signal 188A switches between high level and low level in all time windows.

[0080] Fig.10 (B) is the control in "Mode 5" of "Non-charging Mode". Fig. 9 The detection time is indicated as "always in progress" control. Here, all voltage control signals 186B, 187B, and 188B detect voltage in the first half of the time window of 1 second and stop voltage detection in the second half. However, this control does not set the time window until the voltage of any battery cell is less than 3.0V. If it does not reach 3.0V, the first to third voltage detection circuits 171 to 173 are continuously operated to perform voltage detection as in voltage control signals 186C, 187C, and 188C. If the voltage of any battery cell reaches the discharge stop threshold voltage, the microcomputer 150 detects the voltage via the LD terminal 135 (refer to Figure 4 ) sends a stop instruction signal to the main body of the electrical device. In addition, here, the discharge stop threshold for switching to continuous voltage detection is set to 3.0V, but it is not limited to this voltage and can be appropriately set according to the type of battery cell used.

[0081] Fig.10(C) is the control in "Mode 1" of "Charging Mode". Here, all voltage control signals 186D, 187D, and 188D detect voltage in the first half of the time window of 1 second and stop voltage detection in the second half. However, this control does not set the time window until the voltage of any battery cell rises to 4.1V. When it becomes 4.1V or above, the first to third voltage detection circuits 171 to 173 are continuously operated to perform voltage detection as the voltage control signals 186E, 187E, and 188E do. If the voltage of any battery cell reaches the charge stop threshold voltage, the microcomputer 150 detects the voltage via the LD terminal 135 (refer to Figure 4 ) sends a stop instruction signal to an external charger (not shown). In addition, here, the charging stop threshold for switching to continuous voltage detection is set to 4.1V, but it is not limited to this voltage and can be appropriately set according to the type of battery cell used.

[0082] As described above, according to the present embodiment, since the voltage of each battery cell can be measured by an inexpensive general-purpose microcomputer without using a dedicated protection IC for protecting lithium-ion batteries, it is possible to reduce the cost of the battery pack. In addition, the voltage of each battery cell is divided to be lower than the power supply voltage of the microcomputer and input to the microcomputer, and the power consumption of the generation circuit and the imbalance of each battery cell are suppressed, so that a battery pack with a long life in which the battery cells are not easily unbalanced can be realized. That is, when the voltage of each battery cell is always detected, the power consumption of each battery cell is different, and the battery cell 105 discharges the most, followed by the battery cell 106. Therefore, by performing battery cell voltage detection at different times in each battery cell, the power consumed by the voltage detection circuit can be different in each battery cell, so that the imbalance of each battery cell can be suppressed compared to the case of always detecting.

[0083] [Example 2]

[0084] In the battery pack 100 described in the first embodiment, the input ports (152a to 152c) and the output ports (153a to 153c) are ensured only by the number of battery cells used, so a microcomputer having a port number more than twice the number of battery cells is required. Generally, the more terminals a microcomputer has, the more expensive it is, and on this basis, a larger installation space is required, so when the number of battery cells is increased, the restrictions on installation increase, which may cause the volume of the battery pack to increase. Therefore, in order to reduce the input and output ports of the microcomputer, multiple different functions are allocated to one input port (152), and the multiple functions are switched and executed in a time-sharing manner, thereby reducing the number of required input ports.

[0085] Fig.11FIG. 1 is a circuit diagram of a battery pack 100A having a microcomputer 150. Figure 6 The circuit diagrams shown are substantially the same, but differ in that the signal lines 176A, 177A, and 178A from the first to third voltage detection circuits 171 to 173 are collected and connected to the general input port 152 via one signal line 176. Therefore, the voltage control signals 186F, 187F, and 188F from the first to third voltage detection circuits 171 to 173 are sequentially outputted without duplication.

[0086] Fig.12 (A) is a timing chart of voltage detection by the microcomputer 150 of the battery pack 100A during charging. Fig.12 In (A), the voltage control signals 186F and 187F are turned on at a time interval of 5 seconds, that is, at the time T = 0 to 1 second and 5 to 6 seconds. In addition, the voltage control signal 188F is continuously detected, that is, the voltage control signal 188F is turned on alternately every 0.5 seconds. However, when the voltage control signals 186F to 188F are repeatedly output, the outputs from the first to third voltage detection circuits 171 to 173 will be repeated. Therefore, the microcomputer gives priority to control in a manner that does not repeat them. First, in the time window 0 to 1 second, the voltage control signals 186F to 188F all need to appear. Therefore, only the voltage control signal 188F is turned on during the initial T = 0 to 0.5 seconds, then only the voltage control signal 187F is turned on during T = 0.5 to 1 second, and then only the voltage control signal 186F is turned on during T = 1 to 1.5 seconds. In the next time window, since the voltage control signal 186F has been turned on in the first half, only the voltage control signal 188F is turned on during T = 1.5 to 2 seconds after the end of this part. Only the voltage control signal 188F is turned on in the time windows of 2 seconds, 3 seconds, and 4 seconds, but the turning on is shifted to the second half of the time window at the time window of 2 seconds, so the voltage control signal 188F appears in the second half of the time windows of 2 seconds, 3 seconds, and 4 seconds while maintaining the interval.

[0087] In the 5-second time window, voltage control signals 186F to 188F all need to be turned on. However, according to the relationship between the time windows of 2 seconds, 3 seconds, and 4 seconds, voltage control signal 188F remains disconnected in the first half. Therefore, after voltage control signal 187F is turned on at T=5 to 5.5 seconds and voltage control signal 186F is turned on at T=5.5 to 6 seconds, voltage control signal 188F is restored at T=6 seconds. As a result, voltage control signal 187F does not appear in the 5-second time window, but in essence only includes a stop time of 0.5 seconds, so there is no substantial impact. If control is performed in this way, it is possible to use one input port 152 to input signals from three voltage detection circuits (171 to 173) for processing.

[0088] Fig.12 (B) is a timing diagram of voltage detection by the microcomputer 150 of the battery pack 100A during discharge. During the discharge process, the voltage control signals 188G, 187G, and 186G are alternately turned on at intervals of 0.5 seconds and repeated. By performing voltage detection alternately in this way, the signal lines 176A, 177A, and 178A can be input to the input port 152 of the microcomputer 150 as one signal line 176. In addition, here, the voltage control signals 188G, 187G, and 186G that are turned on are switched at intervals of 0.5 seconds, but the time interval is arbitrary and can be switched at shorter intervals or longer intervals.

[0089] As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to the said embodiment, Various changes are possible within the range which does not deviate from the summary.

Claims

1. A battery pack comprising: a plurality of battery cells connected in series; a plurality of voltage detection units for detecting the voltage of each battery cell; and a control unit having a microcomputer for measuring the voltage of the battery cell based on the output of each voltage detection unit, characterized in that: A switching control circuit is provided in each of the plurality of voltage detection units, and the switching control circuit turns on or off the output from the voltage detection unit to the microcomputer. A voltage dividing circuit is provided on the output side of the voltage detection unit to divide the detected voltage into a voltage lower than the power supply voltage of the control unit. The plurality of battery cells are configured to include at least a first battery cell and a second battery cell from the ground end side. The above-mentioned multiple voltage detection units are connected to a common ground terminal. The first voltage detection unit among the plurality of voltage detection units detects only the voltage of the first battery cell. The second voltage detection unit among the plurality of voltage detection units detects a combined voltage of the first battery cell and the second battery cell. The microcomputer is configured to measure the voltage of the battery cell based on the voltage divided by the voltage dividing circuit. The time intervals for detecting the voltage of each battery cell by the plurality of voltage detecting units can be changed for each of the voltage detecting units according to the state of the battery pack.

2. The battery pack according to claim 1, characterized in that: The plurality of battery cells further includes a third battery cell, The plurality of voltage detection units further include a third voltage detection unit, The third voltage detection unit detects a combined voltage of the first to third battery cells.

3. The battery pack according to claim 1 or 2, characterized in that: The microcomputer has output ports corresponding to the plurality of voltage detection units. The plurality of switching control circuits described above can be switched independently.

4. The battery pack according to claim 1 or 2, characterized in that: The microcomputer has a plurality of input ports corresponding to the plurality of voltage detection units, respectively, or an input port commonly connected to the plurality of voltage detection units. In response to the signal input to the input port, a signal to stop charging or discharging is output to the external electrical device or the charger.

5. The battery pack according to claim 1, characterized in that: During charging of the battery pack by the external charger, control is performed so that the voltage detection execution time of the voltage detection unit is shorter than the voltage detection stop time.

6. The battery pack according to claim 1, characterized in that: In a state where the battery pack is mounted on an external charger, a voltage detection interval of the voltage detection unit during charging is set to a time interval shorter than a voltage detection interval of the voltage detection unit during a waiting period for charging.

7. The battery pack according to claim 1, characterized in that: The control unit does not perform voltage detection by the voltage detection unit when the battery pack is attached to the external charger and charging is completed.

8. The battery pack according to claim 1, characterized in that: When the battery pack is mounted on the main body of the electric device and is not waiting for discharge, the voltage detection by the voltage detection unit is performed at a time interval shorter than a voltage detection stop time.

9. The battery pack according to claim 1, characterized in that: When the battery pack is mounted on the main body of the electric device and is being discharged, the voltage detection unit always performs voltage detection at fixed intervals.

10. An electrical device, characterized in that: The utility model comprises a battery pack mounting portion on which the battery pack according to any one of claims 1 to 9 is mounted, and the working equipment is operated by the electric power from the battery pack.

11. A battery pack comprising: a plurality of battery cells connected in series; a plurality of voltage detection units for detecting the voltage of each battery cell; and a control unit having a microcomputer for measuring the voltage of the battery cell based on the output of each voltage detection unit, characterized in that: A switching control circuit is provided in each of the plurality of voltage detection units, and the switching control circuit turns on or off the output from the voltage detection unit to the microcomputer. A voltage dividing circuit is provided on the output side of the voltage detection unit to divide the detected voltage into a voltage lower than the power supply voltage of the control unit. The microcomputer has: The number of input ports is the same as the number of the battery cells and connected to the voltage detection units respectively; and The number of output ports connected to the switching control circuits is the same as the number of the battery cells.

12. A battery pack comprising: a plurality of battery cells connected in series; a plurality of voltage detection units for detecting the voltage of each battery cell; and a control unit having a microcomputer for measuring the voltage of the battery cell based on the output of each voltage detection unit, characterized in that: A switching control circuit is provided in each of the plurality of voltage detection units, and the switching control circuit turns on or off the output from the voltage detection unit to the microcomputer. A voltage dividing circuit is provided on the output side of the voltage detection unit to divide the detected voltage into a voltage lower than the power supply voltage of the control unit. The plurality of battery cells are configured to include at least a first battery cell, a second battery cell, and a third battery cell from the ground end side. The plurality of voltage detection units are connected to a common ground terminal. The first voltage detection unit among the plurality of voltage detection units detects only the voltage of the first battery cell. The second voltage detection unit among the plurality of voltage detection units detects a combined voltage of the first battery cell and the second battery cell. The third voltage detection unit among the plurality of voltage detection units detects a combined voltage of the first battery cell to the third battery cell. The microcomputer performs voltage detection by the first to third voltage detection units in an unequal manner.

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